Rotary electrostatic microactuator

Abstract

A rotary electrostatic microactuator that includes a substantially planar substrate and a rotatable member overlying the substrate for rotation about an axis of rotation extending perpendicular to the planar substrate. First and second spaced-apart springs and a plurality of comb drive assemblies are included. Each of the comb drive assemblies has a first comb drive member mounted on the substrate and a second comb drive member. Each of the first and second comb drive members are provided with arcuate comb drive fingers. Each of the first and second springs has a first end portion secured to the substrate and a second end portion secured to at least one of the second comb drive members for suspending the second comb drive members and the rotatable member over the substrate. The second comb drive members are movable in a direction of travel about the axis of rotation between a first position in which the comb drive fingers of the first and second comb drive members are not substantially fully interdigitated and a second position in which the comb drive fingers of the first and second comb drive members are substantially fully interdigitated.

Description

SCOPE OF THE INVENTIONThe present invention relates generally to electrostatic actuators and more particularly to rotary electrostatic microactuators with comb drive assemblies.Many early rotating electrostatic motors used a central bearing with various arrangements of electrostatic stators around the motors to effect rotation. Unfortunately, these motors tended to have problems with friction at the central bearing and have had lifetime issues related to wear of the bearing. The motors typically acted as stepper motors where the rotor rotates with an incremental motion as the stator elements are attracted. Thus it was difficult to precisely adjust a plate to a particular angle with such motors.Other angular motors have been described which use flexural elements to support a rotating element. Comb drive fingers are arranged in concentric arcs around a central flexural pivot, so that small angular motion is provided around the pivot. See, for example, D. A. Horsley, et al., "Angular M...

AI Technical Summary

Benefits of technology

In general, it is an object of the present invention to provide a rotary electrostatic microactuator with an improved range of angular motion.

Another object of the invention is to provide a rotary electrostatic microactuator of the above character in which side instability forces in the one or more comb drive assemblies of the microactuator are minimized.

Problems solved by technology

Unfortunately, these motors tended to have problems with friction at the central bearing and have had lifetime issues related to wear of the bearing.

Thus it was difficult to precisely adjust a plate to a particular angle with such motors.

Unfortunately, all of these devices provide a limited angular range of motion.

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